Electric burglar-alarm



(No Model.) 4 sheetsheet 1.

` H.v C. ROOME.

ELBGTRI-G BURGLAR ALARM.

No. 882,489.` Patented May 8, 1888.

IIIIIIIIIIIII n A wlmllwll A I y (No Model.) 4 Sh'eets-1-Sheet 2.

H. G. ROOMB.

liLflRC BURGLAR ALARM.

Patented May 8, 1888.

611mm@ y 2 '(No Model.) 4' Sheets-Sheet 3.

H. C. ROOME.

Y EIETRIG BURGLR ALARM. No. 382,489; Patented May 8, 1888.

zlalwec J'ceqm' f (No Model.) 4 Sheets- Sheet 4.

H. C. ROOME. ELECTRIC .BURGLAR ALARM.

No. 382,489. Patented May-8, 1888.

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Parent @erica HENRY C. ROOME, OF JERSEY CITY, NEW JERSEY.

ELECTRIC BURGLAR-ALARVI.

SPECIFICATION forming part of Letters Fatemi; No. 382,439, dated May 8, 1888.

Application filed September 15, 1884. Serial No. 143,063,

(No model.)

alarms of the kind wherein electric circuits ex tend between a number of buildings, which I shall herein refer to as guarded structures, and an office where watchmen are kept, means being employed to indicate at the office any attempt which may be made to gain access to the guarded structures.

An important object ofthe improvement is to more effectually 4preclude the tampering with the electric circuits aforesaid 4in such manner as to interfere with the transmission of an alarm to the office on an attempt to gain access to a guarded structure being made.

In order to facilitate a clear understanding of my improvement, I shall designate the circuits within the ottlce as internal circuits and the circuits extending to and through the guarded structure as external circuits.

The improvement partly consists in the combination, in an electric burglar-alarm comprising an internal circuit and an external eircuit, of a mechanism at a guarded structure, whereby a number of different resistances may be successively thrown into the external circuit by means of increasing at the office the electric current passing through the circuits, a mechanism at the office, whereby on the increasing of the electric current a number of corresponding resistances will be thrown into the internal circuit, and means located at the office and serving to give an alarm there in case the external circuit is tampered with in an attempt to gain access to the guarded structure. By this feature of my improvement the resistances of the several external circuits extending to and through guarded structures may by a watchman at the ofiice be from time to time changed without occasioning the sounding of any alarmatthe office. Obviously the burglar-alarm will thus be rendered incalculably more safe, because even if burglars should by the treachery of a clerk or servantemployed at a guarded structure or otherwise ascertain the amount of resistance in the structure at the time the same is closed they cannot rely ont-he amount of resistance being the same when the attempt to gain access to the structure is made; and, furthermore, because even it thc resistance which is in the external circuit at the time ofthe commencement of an effort to gain access to the structure is known the change of resistance attempted to be made a few minutes later by a watchman at the office will indicate the burglars presence and ren- -der their knowledge useless.

rIhe improvement also consists in the combination in an electric burglar-alarm, comprising an internal circuit and ancxternal circuit, ot' a mechanism at a guarded structure and a mechanism at the oflice,whercby corresponding resistances may be successively thrown into the external and internal circuits by means of an increase of the electric current passing through the circuits, effected at the office, and a galvanometcr or differential relay-magnet located at the office and serving to give an alarm there in case the equilibrium of the resistances in the externaland internal circuits is disturbed by an attempt to gain access to the guarded structure, anda compound key located at the ofiice, whereby the galvanometer or differential relay-magnet employed for causing the sounding of an alarm may be cut out of the circuits and the electric current passing through t-he circuits may be subsequently increased to operate the mechanisms, whereby the resistances in the circuits are changed. This feature of my improvement will prevent any alarm being given at the oflice in case the mechanism for introducing a different resistance in one circuit operates before the mechanism in the other circuit operates to introduce a corresponding resistance in the latter circuit; and, as it is next to impossibl'eto produce two mechanisms which will start and operate absolutely in unison, this feature of my improvement is of considerable importance.

The improvement also consists in the combination,in an electricburglar-alarm comprising internal circuits at the office, external circuits extending to and through guarded structures, of galvanometers or differential relaymagnets located at the office and connected with the external circuits for the purpose of giving alarms, a mechanism in the office for ICO successively introducing different resistances into one of the internal circuits, a similar mechanism in each of the external circuits for successively introducing different resistances into the said circuits, a system of switches and connections at the oflice so arranged that any one of the galvanometers or differential relaymagnets for giving alarms may be switched out of the circuit inwhich it is ordinarily operative and into a system of circuits comprising a supplemental battery, and the mechanism for introducing different resistances into the internal circuit aforesaid is rendered capable of being used at the office in connection with any one of the mechanisms,whereby difvferent resistances are introduced into the external circuits.

The improvement also consists in the combination, in an electric burglar-alarm comprising internal circuits at the ottice and external circuits extending to and through guarded structures, of galvanometers or differential relay-magnetslocated at the oftice and connected with the external circuits for the purpose of giving alarms, a mechanism arranged in one of the internal circuits and comprising a train of wheels and a controlling electro-magnet, whereby different resistances may be introduced into this. internal circuit, a number of rheostats arranged in the other internal circuits and comprising coils of different resistances, a mechanism arrangedin each of the external circuits and comprising a train of wheels operating under control of an electromagnet for introducing different resistances into the said external circuits, anda system or" switches and connections at the ottice,\vhere by the internal circuit at the oiiiee, which is provided with the train of wheels and resistances, maybe temporarily connected with any of the external circuits and subsequently replaced by one of the internal circuits, which are provided with rheostats. I am thus enabled to use a single mechanism comprising a train of wheels controlled by an electro-magnet in the ofce in conjunction with anumber of such mechanisms in external circuits.

The improvement also consists in the combination, in an electric burglar-alarm comprising an internal circuit and an external circuit, of a mechanism at a guarded structure,where by a number of different resistances may be successively introduced into the external circuit byincreasing at the office the electric current passing through the circuits, a mechanism at the oftice whereby on the increasing of the electric current a number of corresponding resistances will be introduced into the internal circuit, a galvanometer or differential relay-magnet located at the oiiice and serving to give an alarm there in case the external circuit is tampered with in an attempt to gain access to a guarded structure, a mechanism in the external circuit which if short-circuited in an attempt` to gain access to a guarded structure will be maintained shortcircuited, an electro-magnet having apolarized armature, connections, and two batteries adapted to send electric-currents in different directions over the circuit, whereby the said short-circuiting mechanism may be shunted out of the circuit by a watchman at the olice, so as to be rendered temporarily inoperative.

Figure 1 in the accompanying drawings is a diagram illustrative of a burglar-alarm embodying'eertain features of my improvement. Figs. 2 and 2 are diagrams illustrating a burglar-alarm embodying the improvement in a somewhat different form, Fig. 2 representing the different mechanisms at the ofiice, and Fig. 2 representing the corresponding mechanisms in the guarded structures. Fig. 3 is an enlarged plan view of a mechanism for introducing dit't'erent resistances into the internal circuit. Fig. 4t is a sectional side elevation of what l term a short-circuiting mechanism77 employed in the burglar-alarm. Fig. 5 is an. end view of a switch which is employed in the form of burglar-alarm which is illus-A trated in Fig. 2. Fig. 6 is an enlarged edge View of a key-board employed in the burglaralarm.

I will tirst describe the torm otburglur-alarm illustrated in Fig. l.

A A/ A'l designate a galvanometer comprising two coils, A A', which are preferably of equal resistance and tend to deiiect a needle, A2, in different directions. Vhen an electric current passingl through the coil A preponderates over an electric current passing through the coil A, the needle will be detlected to the left, and when an electric current passing through the coil A preponderatcs over an electric current passing through the coil A, the needle will be deflected to the right. In either case the needle will move against a contact-piece and-close'a local circuit, A3, which extends to the pivot of the needle and to contact-points with which the needle operates. This local circuit is provided with a local battery, A4, andan electro-magnetic bell, A5. 'The latter may or may not be rheotomic.. An audible alarm will be given whenever the galvanometer-needle closes the local circuit. lllhe needle by its vibrations gives a visual alarm. The circuit which passes through the coil A of the galvanometer is the one which l designate as the internal77 circuit, and theone passing through the coil A is that which I designate as the-external circuit. The galvanometer-needle will vibrate only when the resistance of the two circuits is different, and while the resistances in the two circuits are in equilibrium the needle will be held midway between the contact-pieces of the localcircuit.

The main electric circuit extends from a battery, B, along la wire, C. This wire is interrupted and connectedto the coils of an electro-magnet, O, the purpose of which will be presentlyV described. From the electromagnet O the said wire extends to a metallic contact-piece, e, which is made in the form of a keeper for a metallic key, E. Thence the circuit extends along the wire C to the coil A of the galvanometer; thence through the said coil and along the wire G2 to a resistance-coil, C3, and thence along a wire, C4, to a metallic finger on a shaft, a, comprised in a mechanism, F, for introducing different resistances into the internal circuit.` From this shaft a the circuit is continued to one of a number of metallic springs, b b', &c., comprised in said mechanism F; thence to one of a number of resistance-coils, c c', duc., comprised in said mechanism; thence along a wire, G, which connects the said resistance-coils c c', &e.,with a metallic key E', thence along this key to a contact-piece, e, which is made in the form of a keeper therefor, and thence by awire, G', to the 4battery B. The wire G', near where it connects with the battery B, is connected by a wire, G5, to any earth'plate, H. The electric current divides at the point where the wire C connects with the coil A of the galvanometer. Part of the electric current passes through the coil A and thence along the line C?. Another part of the electric current passes along a wire, C6, extending from the wire C to the coil A of the galvanometer, and thence through the coil A and to a wire, I, formingpart of the external circuit.

The wire I is connected to one end of the coils of an electro-magnet, Q, having a polar ized armature, M. The object of this electro magnet and its appurtenances I will describe fully hereinafter. l From the other end of the coils of this electro-magnet a wire, l', extends to a binding-post, q, ofa short-circuiting mechanism, It R', the., the purpose of which will be explained presently. A wire, I2, extends from a binding-post, q', ofthe short-cireuiting mechanism to the contactpiecef of a pair of metallic contactpieces,ff, forming a circuitcloser on an electric envelope, J, designed to inelose a sale in a guarded structure. The contactpiece f is aiiixed to the body ot' the envelope J, and the contact piecef is aiixed to the door of the envelope. The contact-piece 45 f may be made in thedform of a hook having the shank bent around into a curve which is concentric with the pintles of the hinges by which the door is connected to the body of the envelope; hence when the door is closed the hook-like end of the contact piecef will A be separated from the eontactpiece f, and

when the door is opened the hook-like end ot' the contactpiece f willimpinge against l the contactpiecef. From the wire I2 or the y contact-piecej" a wire, 13, extends to the coils of an electro-magnet, d, comprised in a mechanism, F', whereby different resistances are introduced into the external circuit. Fiom the coils of the electro-magnet d the external circuit extends along a wire, 1*, to a metallic finger on the shaft a ofthe mechanism Fjust mentioned; thence the external circuit extends to one ol' a series of metallic springs, b b', cac., comprised in this mechanism, with which the said iinger of the shaft a maybe in contact; thence to one of a number of resistancecoils, c c', Sto., comprised in the mechanism F', and thence along a wire, 'KL This wire K extends from these resistance-coils c c', Src., to the c0ntact-piecef of the electric envelope J, and thence to an earth-plate, H. The circuit is completed to the battery B through the earth from the i earth-plate I-l to the earthplate H.

C designates a wire leading from a switch, G19. This switch C19 has two contact-pieces with which batteries B Bare connected by suitable wires. These batteries B B5 are intended to be of equal strength, but they are capable of producing electric currents in opposite directions through the switch C1 and thence to the wires in circuit with it. These batteries are of greater potential than the battery B. These batteries BB5 are connected by wires with an earthplate, H2. The object of providing for sending an electric current in reverse directions over the switch G1 will appear later. The Wire Cu extends to a contactpiece, c2, arranged below a metallic key, EZ, which normally is out ot' contact with this contact-piece and in contact with akeeper, e3, which is not in the electric circuit. A wire, C, extends from the metallic key E2 to the coils of the electrovmagnct d of the mechanism F, whereby different resistances are introduced into the internal circuit. The other end of the coils of the electro-magnet d is connected by a wire, L, to the wire I ofthe external eircuit.

I may here remark that the keys iE and E are normally in contact with the contact-pieces e' e, which constitute theirkeepers. The key E has across-bar, g, of insulating material, which is adapted to impinge against the keys E E2, so that these keys E 132 may be depressed by depressing the key E. These keys arein effect a single compound key. The key E may be depressed by clock-work periodically ii desirable.

Each of the mechanisms F F comprises a train of gear-wheels, h, which havecombined with `them a weight or a spring,whereby they are caused to rotate. These wheels also have IIO combined with them a retarding device-such as a fly,jworpreventing them from rotating too rapidly. The springs b b', Ste., are arranged upon a cireulardisk of insulating material, k, so that their ends will project in the Way of the metallic linger ofthe shaft c. The rotation of the wheels is controlled by means of a lever, Z, connected to the armature of the electro-magnet d and acting in conjunction with a pin, m, on awhcel, h, comprised in the train of gcarwheels 7L. 'Vhen the electromagnet d is energized, the armature is attracted and the train of gear-wheels permitted to rotate. The resistance of the coils of the electro magnet d is such that the electric eurrent from the battery B will not energize it sufficiently to enable it to attract its armature. It is only rendered operative when the batrtery B or B5 is put in circuit by depressing the key E2 upon the contact-pieee c2, which is only done momentarily to effect the release of` 4 being higher.

the train of wheels z. The Wheels, when released, therefore run only long enough for the wheel h to make a single complete rotation and be arrested again by the lever Z.- This is only long enough for the metallic finger of the shaft a to move from one to another of the metallic springs b b', 85o.

rIhe resistance coils c c', die., are severally made of different resistances, and those of the mechanism F are made to correspond in resistance and order of succession with those of the mechanism F. The resistancecoil Ca is placed in the internal circuit to equalize the resistance which would otherwise exist in the external circuit over and above the resistance of the internal circuit, owing to `the greater length of wire in the external circuit and the presence of the electro-magnet Q and the electro-magnet d of the mechanism F normally in tne external circuit.

The key E is allowed to rise above the level of the other keys, E E2, owing to its keeper e When the key E is depressed, contact is broken between it and its keeper e,

and subsequently the other keys are depressed,

so that they will break contact with their keepers,and the key E? will impinge on its contactpiece e2. Owing to this, the battery B is first cut out of circuit; next the communication of the key E through the wires G C5 with the earth-plate His broken, and finally the battery B or B5 is brought into circuit with the key E. Were it not for breaking the communication of the key E through the wires GC5 with the earth-plate H prior to the bringing of the battery B or B5 into circuit,the electric current of the battery B might pass along the Wire Lthence along the coils of the galvanometer A A A2, thence along the wire C2 to the mechanism F, and thence by the wire G, key E', and wires G O5 to the earth-plate H. This would be objeetionable,because it would cause a deiiection of the galvanometer needle. When thekeys E E E2 have been depressed, as described, the electric current from the battery B' or B5 will pass 'to the key E5; thence along the Wire C to the coils of the electromagnet d of the mechanism F; thence along the wire L to the Wire I, along the wire I to the electro-magnetQ; thencealong thewire I to the binding-postqot'the short-circuiting mechanism,fR B,&c.; thence from the binding-post q of theshort-circuiting mechanism to the wire Rand along the latter to the contactpiecef of the electric envelope J; thence along the Wire l3 to the electromagnet d of the mechanism F; thence along the'wi're I4 to the finger of the shaft a of the mechanism F; thence to whichever one of the springs b b', &c., of the mechanism F the linger of the shaft a of said mechanism F may happen to be in contact with; thence to thecorresponding resistancecoil, c c', Src., of the mechanism F, and thence along the wire K to the contact-piecef andthe earth-plate H.

The trains of wheels comprised in the mechanisms F F will then be released because the electro-magnets d will then attract their armatures,and thereby cause the armature-lever to release the wheels h,as explained before. The keys E E E2 will only be kept in their de pressed positions momentarily,so as to enable such of the resistance-coils c c', 8vo., as were in circuit to be cut out of circuit and other of these coils to be introduced into circuit. When the keys E E E2 are allowed to rise to their normal positions, the key E2 breaks contact with its contact-point c2 and cuts oli the battery B, the key E rises to its keeper c, and the key E rises to its keeper e and establishes communication between the key and the battery B. As the battery B is by the above-described operation of the keys E E E2 cut otf from both coils of the galvanometer before the resistance in the circuits is changed and is not reinstated in the circuit until after the change of resistance in the circuits has been made, the galvanometer-needle A2 will not be affected even ifa resistance-coil beintroduced by the mechanism in one circuit with greater alacrity than by the mechanism in the other circuit, because the coils of the galvanometer will not be influenced by any battery-current until the resistances in both circuits have been equalized.

It is obvious that by frequently changingthe resistances inthe circuits it is made practically impossible for a burglar to effect an entrance into the guarded structure without giving an alarm at the office, even though he happen to learn what resistance was in circuit at any particular time,because ifhe should introduce into a circuit intended to replace the external circuit the resistance of which he had obtained knowledge, that would avail him nothing if the resistance of the circuits should have been changed subsequently to the time when he obtained knowledge of the resistance used.

l In this example of my improvement a scparate mechanism, F, and set of keys E E E2` need to be employed in the office for each guarded structure. Vhile I have represented thc burglanalarm in connection with but one guarded structure, I intend to use it in con` 'lOO nectionvwith a number of guarded structures v and o ne office.

Itis hardly necessary to remark that if the battery B should become inoperative the Whole efciency of the burglar alarm would be impaired, because the galvanometer needle would not be d eected, and hence no alarms would be given at the oliice, even if the internal or external circuit were severed. It is therefore very desirable to provide means for indicating such an accident. I will now describe a contrivance devised to secure that end.5 I have already explained that the wire C is connected to the coils of the electro-magnet O. It will be understood, therefore, that the electric current from the battery B passes along the'coils of the electro-magnet O. From there it extends along the wire C to the keeper eof thekey E. The electro magnet O has an ar mature, O', shown as pivoted in place at one end and adapted to swing toward and from the electro-magnet. It is drawn toward the electromagnet by the force of the latter so long as the battery B is in working order; but if anything happens to impair the working of this battery, a spring, O2,will move the armature away from the electromagnet. W'hen this occurs, a contact-piece with which the armature is providedv will be moved into contact with a contact-piece, O, comprised in a local electric circuit,r. The other end of this electric circuit r is connected with the armature O'. In the electric circuit r are a battery, B3, and an electro-magnetic bell, r'. Vhenever the electric circuit r is closed,the electromagnetic bell is sounded,and in that way an alarm is given as tothe failure of the battery B to work. The electro-magnetic bell may or may not be rheotomic.

I will now describe the modification of my improvement shown in Fig. 2, premising that the same illustrates the improvement in conjunction with two guarded structures. Here one mechanism, F, and a single set of keys, EEEZ, in the office, similar to the mechanism F and the keys E E E2 in Fig. l, hereinbefore described, will sufiice for use, in conjunction with mechanisms F, in several guarded structures made like thc mechanism F, before explained.

M designates a switch located in the office and consisting of a cylinder or block, p, of wood or other non-conducting material, having at the endsjournals mounted in bearings, permitting it to be adjusted axially in either of two positions. Upon the face of' this block are metallic plates a n2 n3 at a5 n. A number of springs, o' o2 o3 o4 o5 0" o7 oa o 01, extending from the base-piecep' of the switch, bear on the face of the block p. The arrangement of the metallic plates will be madeclear hereinafter.

N designates a rheostat compos-ed of a number of resistance coils corresponding to the resistance-coils c c', 85e., ofthe mechanisms F F and arranged in the same order. One end of its coils is connected by a wire, CB, to an earthplate, H5. A wire, C7, leading from the spring ol, may be connected. with the other end`of` either of the coils of this rheostat by fitting a plug, with which such wire is provided, into any one of a series of holes in the rheostat.

. I will assume for the present that the block p of the switch Mis turned, so that its handle p will be in an upright position.

An electric battery, B2, is connected at one pole with an eartlrplatc, H", and at the other i pole with one end of the coil of an electrosistance in the coil of the mechanism F', which is in the external circuit through which the current is passing. The resistance-coil of the rheostat, which is in the internal circuit, will then balance the resistance-coil of the mechanism F in the guarded structure, and the resistancecoil G3 will counterbalance any extra resistance that may exist in the external cir- A cuit owing to extra length of wire and the presence of the coils of the electro-magnet Q and the electromagnet d of the mechanism F. Hence there will be no deflection of the galvanometerneedle.

If it is desired to change the resistance in the internal and external circuits belonging to any guarded structure, the block p Aof, the switch M belonging to that guarded structure is shifted so as to' bring its handle pZ into a horizontal position. This will cause the springs o oZ to make contact with the metal plate a', the springs o3 ol to make contact with the plate n, the springs o5 o to make contact with the plate a, the springs o4Q oJ to make contact with the plate a, and the springs oT 0" to make contact with the block p. The battery B2 is thus 'cut oft' from communication with the wire C. A wire, C, extending between the wire C and the spring o?, is, however, put into communication with a wire, C, which leads from the spring o' to the earth-plate H5,

and hence the electro-magnet O is kept enerv gized and no alarm will be sounded by the electro-magnetic bell r. The metal plate a is so arranged on the block p that it will be brought in contact with the springs o ol before the springs o9 ow have broken contact with the metal plate a, in order that the electro magnet O will always be kept charged,and no alarm will be given by the bell r when the switch -block is thus shifted. rlhe electromagnet O, the appurtenances thereof, the circuit r, and the electro-magnetic bell fr are the same in construction and function as the correspondingl y lettered parts illustrated in Fig. l.

The communication between the rheostatN and the wire G2 will be cut otI when lheswitch M is thus manipulated. The electric current will now pass from abattery, B, along a wire to the contact-piece or keeper e of the key E, thence along this wire to awire, C, and thence to the spring o23 of the switch M. From the spring oE it extends over the plate a4 to the spring o, thence along the wire G to the coil A of the galvanometer. Here it divides, part passing through the coil A and thence along the wire G2, and part passing through the coil A` and thence along the wire I.

The electric current which passes to the wire C2 passes thence to and through the resistancecoil C3, thence further along the wire C2 to the spring o, thence over the plate a3 to the spring o5, thence along a wire, C10, to the key E, and thence to the keeper or contact-piece e of the latter. From the keeper or contact-piece e of this key E a wire, C4, extends to the shaft a of the mechanism F. vFrom the resistance- Coils c c', Ste., of this mechanism F a wire, G, extends to an earth-plate H. The battery B is shown as connected by another wire with the same earth-plate H. From the key E2 a wire, C, extends to the spring o'r1 of the switch M. It will be borne in mind that when the block of this switch occupies the position lastV described the plate n2 establishes communication between the spring 03 and the spring o". A wire, L, extends fromthe spring o4 and connects with the wire I. rlhe contact-piece e2 of the key E2 is connected by a wire, C, with one endof the coils ofthe electro-magnet d of the mechanism F, before mentioned. The other end of the coils of the said electro-magnet d is connected with a switch, C19, which is like the switch similarly lettered in Fig. 1. This switch has two contact-pieces connected by wires with batteries B' B5. These batteries are also connected with an earth-plate, H2. By

shifting the switch onto either oi' the contactpieces one or the other of the batteries may be put into communication with the contactpiece e2 ot' the key E2. When the key E2 is depressed so as to impinge against its contactpiece e2, it will be put into electrical communication with whichever of the batteries B or B5 happens to be connected with the contact-piece ezof the said key. Ordinarily the battery B will be connected to the contactpiece e2 of the key; but under certain circumstances, hereinafter to be fully discussed, the battery B will be connected to the said contact-piece e. Both the batteries B B5 are of the same size; but they are adapted to send electric currents in reverse directions over the line.

If while the block ofthe switch M occupies the position last described the key E be momentarily depressed to its full limit, said key will loe removed from its contact-piece e, and the battery B will be cut out, the key E will be separated from its contact-piece e', and communication cut oft between the wires Clo vand Gf, the mechanism F, and the earth; hence there will no longer be any communication between the coil A of the galvanometer and the earth.` rIhe key E when depressed thus causes `the key *2 to make a contact with its contact-piece e2. During this contact an electric current will pass from the battery B or B through the electro-magnet d of the mechanism F, the key E2, the wire C15, the spring 03, the plate n?, and spring o4 of the switch M, the wire L,.and along the wire I. From thence the electric current will pass tothe electromagnet Q; thence to or-past the short-circuiting mechanism B lt', 85e.; thence to the contact-piecesff of the electric envelope J-and the mechanism F and to the earth, all as I have explained in relation to Fig. l.

Bothmechanisms F F commence runningk as soon as the electric current is caused to flow by the operation of the key E2, and the resistance in the internal and external circuits is thereby changed. Suppose the mechanisms F F have stopped with their resistance-coils c3 in circuit. This may be Vascertained by looking at the mechanism F inthe office. The plug of the wire CY will then be inserted in the rheostat in such hole as to cause the proper coil thereof to be in circuit. The block p of the switch M is now reversed so as to bring its handle 19? into an upright position. y shifting the switch-block the keys E E E2 and the mechanism F will be cut out of the circuit, and the battery B2, the appurtenances thereof, and the rheostat N will be thrown into circuit. It will be understood that the change in the resistance has been made without detiecting the needle of the galvancmeter. The resistancesin theinternal and external circuits will now be equal.

I have designated the external circuits for the two guarded structures shown and the appurtenances of these two external circuits by the same letters of reference. The foregoing description maybe regarded as having related toeither. It will of course be understood that there is an internalvcircuit in the ofce for each external circuit. After the keys E E E2 and the mechanism Fhave been used in conjunction with one external circuit they may be similarly used with the other, the necessary initial operation for this purpose being merely to shift the block of the switch M in such way as to bring its handle into a horizontal position,.and the subsequent operations being exactly as I have already described in connection with the guarded structure first described. The circuits of many guarded structures may be treated in the same way with the use of the one set of keys E E E2 and the single mechanism F.

It will be seen that the single set of keys E E E2 are similarly connected with the circuitsl of the twoguarded structures shown. The

circuits for all the guarded structures' whichr will be used with this single set of keys E E Il2 will be similarly connected with the keys. I will now give a detailed description ofthe electro-magnetQhaving a polarized armature, and the'short-circuiting mechanism as used in the burglar-alarm shown in both Figs. l and 2. I Ihave already explained that the wire I is connected to one end of the coils of the electromagnet Q; that a wire, I', leads from the other end of the coils of this electro-magnet to the binding-post q of the short-circuiting mechan` ism, and that a wire, I2, leads from the binding-post g of the short-circuiting mechanism to the contact-piecef ofthe electric envelope By thus permanent magnet.

J. The armature Q of the electro-magnet Q is polarized-011, in other words, consists of a lt is fulcrumed between the ends to a metallic support arranged about midway between thepoles ofthe electro-magnet Q. lt can therefore rock toward either pole of the electro-magnet Q. A wire, l5, eX- tends from the wire l to a contact-piece, Q2, mounted upon a suitable support. armature Q is rocked in one direction, it impingcs upon the contact-piece Q2. When rocked in the other direction, it is separated from the contact-piece QZ. A wire, la, leads from the metallic support of the armature Q to the wire l2, which extends from the bindingpost q' of the short-circniting mechanism tothe contactpiecef of the electric envelope J. W'hen the switch G (see Figs. l and 2) is in communication with the battery B,the electro-magnet Q will be so energized as to rock its armature Q' away from the contact-piece Q2. Consequently the electric cnrrentfrom said battery will pass from the coils of the electro-magnet Q to the Wire l; thence into the short circuitingmechanisrn R It, 85e., and then'ce along the wire l2. to the contact-piece f ofthe electric envelope J. If, however, the switch C19 be put into communication with the battery B5, the electro-magnet Q will be so energized that it will rock its armature Q against the contact-piece Qi. Then the electric current will pass from the coils of the electro-magnet Q to the wire l', thence to the wire l5 and contact-piece Q2, thence along the armature Q', thence along the metal support to which the said armature is fulcrumed, and thence along the wire l6 to the wire l2, which leads to the contact-piecef of the electric envelope J. In such case the short-circuiting mechanism is shunted out.

After describing the short-circuiting mechanism 'i will make clear the object of sometimes thus shunting it.

From the binding-screw q, with which'the wire l is connected, a wire extends to a circuit-breaker consisting of a resilient metallic strip, R', secured at or near one end to the base-piece R, and provided with a thumb-piece or button, r2, whereby it may be manipulated. This circuit-breaker is combined with a keeper, R2, consisting of a metal arm projecting over the circuit-breaker, so that the latter will when in its normal position maintain ,a contact with it. This keeper may Aloe pivoted to the base-piece R so that it can be swung aside out of contact with the circuitbreaker when desirable to retain the circuit broken for any length of time without holding the circuitbreaker depressed. Frein the keeper R2 a wire, t3, extends lo an electro magnet, R", whence a wire, R, extends to the bindingscrew q'. The wire l2 extends to the contactpieeef ofthe electric envelope J, as I have already explained. From the contaetpiece f circuit.

When the d a wire, lt, leads to the metallic linger on the shaft a ofthe mechanism F. Thence, as I have shown, the electric circuit is continued through one of the springs b b', te., and one of the coils' c c', Src., of the mechanism F', and thence along the wire K tothe contact-piecef and the earth-plate l-l. A wire, I7, connects the earthplate H with the binding-post q2 of the shortcircuiting mechanism.

RGdesignates a vibratory armature arranged in proximity to one end of the electro-magnet R* and pivoted to a supporting-bracket, so that it can be attracted by the magnet into contact with it, or, when released, may swing away from it.

Extending from the armature R, (see particularly Fig. 4,) in this instance above the same, is an arm, R7, of conducting material- 'such as metalwhich when the armature is attracted to the electro-magnet comes in contact with an arm, R8, of conducting material, extending from a post, R9, of conducting material, erected on the base-piece R. A wire, Rw, extends from the armature R6 to the wire R5, which is fastened, as here shown,.in the binding-screw g', and another wire, R, extends from the post R9 to the binding-screw q2, connecting there with the wire ll, which leads to thcearth-plate H. Vhen the windows and doors of the structure are closed properly, the electric current will enter on the line-wire I', pass through the circuit-breaker R', keeper R2, and wire R3 to the electromagnet R4. From thence it passes along wire R5 to wire l2,to the contactpiece f of the electric envelope J; thence along the wire l3 and the coils of the electro-magnet cl, comprised in the mechanism F'; thence along the wire l* to the shaft a of the said mechanism F, and thence through a TOO spring, b or b, Snc., and coil c or c', Src., to the wire K, and along it to the earth-plate H. Then any momentary change in the resistance of the circuit outside the structure will cause only a momentary alarm to be given at the office with which the line-wire l communicates. If, however, the electric envelope be opened, the electric circuit will be short-circuited throughthe contactpointsff, and the coil c orc, tif-c., of the mechanism F', which was formerly in circuit, will be shunted out.

The electromagnetR must be so constructed and the armature RG so adjusted in respect to its distance from the electro-magnet and the strength of the spring,whereby it is to be returned toits normal position, that when an electric current is flowing through one of the coils c c', Src., of the mechanism F' from the battery B said armature will not be attracted, but that when the coil c or c', Src., which was in circuit is shunted out by the opening of the electric envelope the armature will be attracted. YVhenever the electric circuit is IIO short-circuited, through the contact-pointsf 13o f and the armature lt attracted to the electro-magnet, the electric current will be shortcircuited again, this time thronghthe'wire R5 to the wire R10, from the latter to the arm thence through the post It and wire It to the wire 17,(see Fig. 2,) and to the ground. In consequence of the latter short-circuiting the electro-magnet will hold the armature evenif the electric envelope after being opened be instantly closed again, because the electric current will take the shorter circuit, and the galvanometer-needle A2 will continue to close the local circuit and cause the bell Afto sound an alarm/until the existing short circuit is broken by the operator at the office opening the line or otherwise and the release of the armature effected,whereupon the circuit mayv be reinstated through a coil, c or c', 8vo., of the mechanism F,and the mechanism in thestructure to be guarded will be in condition for further use.

The short alarm given through a momentary change yin the resistance of the electric circuit from any accidental or other cause outside the guarded structure, and the long continued alarm given through a change in the resistance occasioned at or in the said structure from short-circuiting out a coil, c or c', Src., of the mechanism F may be easily distinguished from each other.

Although not essential, I have shown combined with the electro-magnet R4 (see particularly Fig. 4) an armature, R12, carrying a hammer, R13, operating abell, It, and conveying to inmates of the guarded structure'some preconcerted message from the operator, or notifying them that their attention to the operator is desired. This armature R12 is so adjusted in respect to its distance and the force of the spring,whereby it is retracted, that an electric current of sufficient force to cause the electro-magnet to attract the armature R'iwill produce no effect on the armature R12. I therefore use the battery B (see Figs. 1 and 2) when the bell R is to be operated.

On the topl of the bell I have also shown an arm or pointer, R15, and extending from the arm R7 an indicator, R1, which, by being in contact With or close proximity to the pointer, or by being swung away therefrom, Will indicate whether the doors and windows of the structure to be guarded are all closed by showing whether the electric circuit is short-circuited within the structure.

The object of using the battery B5 as well as the battery B and of employing in conjunction with said battery B5 the electro-mag net Q, having a polarized armature and the appurtenances of these devices, is to enable a watchman at the office to shunt the shortcir cuiting mechanism out of circuit and still availhimself of a powerful battery for operating mechanisms, whereby different resistances Will be introduced into circuit.

Differential relay-magne1s would be equiva lents for the galvanometers A A A2.

To conduce to clearness, Ihave drawn lines around the parts illustrated by Figs. 1 and 2, which are in the guarded structures, and marked these lines with the words guarded structures.7 Likewise I have drawn lines around devices located in the office and marked the same with the word Office I am aware of United States Letters Patent to J. Tourney for electric burglar-alarms, No. 289,471, December 4,1883, and I do not herein lay claim to anything claimed therein.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. In an electric burglar-alarm comprising an internal circuit and an external circuit, the combination of a set of variable resistances in connection with .the internal circuit, a set of variable resistances in connection with the external circuit, mechanism for varying the resistances in the internal and external circuits at predetermined intervals, a supplemental source of electric energy, and mechanism for throwing the supplemental energy into connection with the variable resistances at pleasA ure, substantially as set forth. v, 2. In an electric burglar-alarm comprising an internal circuit and an external circuit, the combination of a set of variable resistancesin connection with the internal circuit, aset of variable resistances in connection with the external circuit, mechanism for varying the resistances at predetermined intervals, a supplemental battery, a switch for throwing the supplemental battery into and out of connection with the variable resistances, and an alarm under the influence ofthe internal and external circuits, whereby attention is called to any disturbance in the resistances in the external circuits, substantially as set forth.

3. In an electric burglar-alarm comprising an internal circuit and an external circuit, the combination of a set of variable resistances in connection with the external circuit, andaset of corresponding variable resistances in connection With the internal circuit, mechanism for changing thc resistances at predetermined intervals, a 'supplemental source of electric energy, means for throwing said supplemental energy into connection with the said variable resistances, a galvanometer or analogous device located under the influence of both the internal and external circuits and held normally in equilibrium thereby, and a compound key in connection with the internal and the external circuits, whereby the internal circuit may be broken when the supplemental elec'- tric energy is thrown into connection with the variable resistances, substantially as set forth.

4. In an electric burglar-alarm comprising internal circuits at the office and external circuits extending to and through guarded structures, the combination of a galvanometer or analogous device located at the office and connected with the external circuits for the purpose of giving alarm, a set of variable resistances in connection with one of the internal circuits, mechanism in connection with the set of variable'resistances for successively introducing different resistances into one of the internal circuits, acorresponding set of variable resistances in each of the external circuits,

IOO

IIO

mechanism for successively introducing dierent resistances into the said circuits, a supplemental battery, a switch to throw the supplemental battery into and outof connection with the set of variable resistances, switches for throwing any one ofthe galvanometers or analogous devices at the ofce out of its normal circuit and into the circuit comprising the supplemental battery, and a compound key for manipulating the several circuits, subst-antially as set forth.

`5. In an electric burglar'alarrn comprising internal circuits at the office and external circuits extending to and through guarded structures, the combination of a galvanometer or analogous device located at the oiice and connected with the external circuits for the purpose of giving alarm, a set of variable resistances in connection with one of the internal circuits, a train of wheels including a switchwheel, and controlling electro-magnet for throwing the variable resistances into and out of circuit, adjustable rheostats arranged in other internal circuits, a set of variable resistances in connection with each of the external circuits, a train of wheels including a switch-wheel, and a controlling electro-magnet, in connection with each of the external sets of variable resistances for throwing the different resistances into and out of circuit, and a system of switches and connections at the office, whereby the set of variable resistances at the office may be temporarily con nected with any of the external circuits and subsequently replaced by the circuit provided with the rheostats, substantially as set forth.

6. In an electric burglaralarm comprising an internal circuit and an external circuit, the combination of a set of variable resistances in connection with the external circuit, mechanisms for introducing the several resistances successively into the externalcircuit, a set of variable resistances in connection with thenternal circuit, mechanism for introducing the different resistances successively into the internal circuit, a supplemental battery for setting in motion the 'aforesaid mechanisms, a switch for throwing said battery into and out of connection with the sets of variable resistances, a galvanometer or analogous device under the iniiuence of the internal and external circuits, and adapted to give an alarm in the event of a change in the resstances of the internal and external circuits, a short-circuiting mechanism in connection with the external circuit, an electro-magnet having a polarized armature, a battery arranged to send an e1ec tric current in the opposite direction from the said supplementary battery, and connections leadingfrom the magnet, having the polarized armature to the battery arranged to send a reverse current and to thelset of variable resistances in the external circuit, whereby the said short circuiting mechanism may be shunted out of its circuit by the watchman at the office.

HENRY C. ROOME.

Witnesses:

W. G. LIrsEY, E. T. ROCHE. 

